In order to mould the tread of a tire, it is known practice to use moulding elements fixed in a mould. What is meant by a moulding element is any element of the mould which has a moulding surface that allows part of the tread of a tire to be moulded. A moulding element can thus be a block fitted on a segment of the mould or else a rib attached to the radially inner surface of the mould.
It is possible to create a moulding element using a selective fusion method more commonly referred to as sintering. This method uses a beam of energy to fuse a metallic powder. A “beam of energy” means electromagnetic radiation (for example a laser beam) or a beam of particles (for example an electron beam).
A sintering method using a laser, referred to below as a laser sintering method, is known from document EP1641580. In that document, a first layer of metallic powder is spread on a plate. All or some of the particles of this first layer of powder are then agglomerated by the beam of a laser according to the shape of the object that is to be obtained. Once this step has been performed, a second layer of powder is spread on the first layer of powder so that it can be selectively fused in turn using the laser. By repeating these operations of spreading a layer and fusing using a laser, a sintered object is built up layer by layer.
Such a sintered object is shown notably in FIG. 3 of document EP0868955. In that figure, the layered structure of the sintered object is easily distinguished, said sintered object being a moulded element intended to be attached inside a mould for a tire. However, this layered structure causes level lines which are the mirror image of this structure to appear on the tread surface of the moulded tire. This phenomenon of level lines is augmented by the curvilinear nature of the mould. These level lines give the tire an unattractive appearance.
There is thus a need to provide a solution that makes it possible to keep using the laser sintering method in order to manufacture the mould for moulding the tire, while attempting to improve the appearance of the tire.